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July 26, 2011

PhD Student Measures How Fast Our Universe Is Expanding

by Sam Savage

An Australian PhD student has created the most accurate measurements for determining how fast the Universe is expanding.

Florian Beutler, a PhD candidate with the International Center for Radio Astronomy Research (ICRAR) at the University of Western Australia, has calculated how fast the Universe is growing by measuring the Hubble constant.

"The Hubble constant is a key number in astronomy because it's used to calculate the size and age of the Universe," Beutler said in a statement.

As the Universe grows, it carries other galaxies farther from Earth. The Hubble constant links how fast galaxies are moving with how far they are from us.

The speed and direction of a galaxy can be measured by analyzing light coming from that galaxy. Astronomers observe the brightness of individual objects within the galaxy and using what is already known about an object to calculate how far away the galaxy could be.

However, Beutler approached the problem differently. He used data from a survey of over 125,000 galaxies carried out with the U.K. Schmidt Telescope in eastern Australia.

Beutler used a measurement of the clustering of the galaxies surveyed, plus other information from observations of the early Universe to measure the Hubble constant.

"This way of determining the Hubble constant is as direct and precise as other methods, and provides an independent verification of them," Professor Matthew Colless, Director of the Australian Astronomical Observatory and one of Beutler's co-authors, said in a press release.

"The new measurement agrees well with previous ones, and provides a strong check on previous work."

Beutler's new measurement can be refined even further by using data from larger galaxy surveys.

"Big surveys, like the one used for this work, generate numerous scientific outcomes for astronomers internationally," Professor Lister Staveley-Smith, ICRAR's Deputy Director of Science, said in a press release.

Beutler's work was published in the Monthly Notices of the Royal Astronomy Society Journal.

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Image Caption: The 6df Galaxy Survey data, each dot is a galaxy and Earth is at the centre of the sphere.